From Seawater to Jet Fuel

U.S. Navy Studies New Ways to Propel Carrier Aircraft

Oct. 25, 2012 - 08:01PM
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The U.S. Navy’s next source of renewable fuel is in pretty ample supply: the ocean.

The Naval Research Laboratory and the Office of Naval Research are working on a project that would turn ocean water into JP-5 aviation fuel, the lifeblood for all of the Navy’s aircraft.

The technology is about a decade away from becoming a reality, researchers say. But if it worked, it would be a major pivot in the way the Navy operates.

Ocean fuel would allow a carrier air wing to fly longer. It would protect ships from risky replenishments at sea. And it would reduce reliance on a fluctuating petroleum market.

In short: It would revolutionize the way carrier air wings fly, the way carrier strike groups deploy and the way Military Sealift Command provides some 600 million gallons of fuel to ships around the world.

As one study in the Journal of Renewable and Sustainable Energy put it, turning the ocean into fuel could have a major impact on operations and logistics.

“In-theater, synthetic fuel production is a ‘game changing’ proposition that could offer the Navy significant logistical, tactical and operational advantages by reducing the Department of Defense’s dependence on increasingly expensive fossil fuels and by reducing fuel logistic tails and their vulnerabilities resulting from fuel delivery at sea,” the study’s authors wrote.

But by no means will this be an easy task for researchers.

The process hinges on the ability to isolate molecules in ocean water, then rearrange their atoms into JP-5, the fuel that not only powers Navy aircraft but is also approved for ship engines.

According to the journal article, written by Navy researchers, 100,000 gallons of JP-5 could be made in a day by combining carbon dioxide and hydrogen that’s been extracted from water in a process that creates water, heat and, most importantly, synthetic hydrocarbon, or fuel. Theoretically, the process could be tailored to produce any sort of hydrocarbon fuel, not just JP-5, according to the report.

The leftover water and heat generated could be harnessed and recycled into the system, making it more efficient.

This process would require an outside energy source to cause the reactions. Nuclear power systems, such as the ones used on aircraft carriers and submarines, could be one option. Another could be ocean thermal energy conversion, a process in which the temperature differences between warm water near the ocean’s surface and colder water at deeper depths are used to turn an engine and create electricity.

The study doesn’t answer some big questions, however.

For example, how would all the necessary equipment to process hundreds of thousands of gallons of ocean water per day fit on an aircraft carrier? To be determined.

“The key is funding research to reduce the power needed for the process, so more fuel can be made,” said Heather Willauer, a Naval Research Laboratory chemist and one of the study’s authors. “In addition, research focus should be directed toward reducing the size, weight and footprint of the technologies to make it feasible for a sea-based process.”

The analysis estimated fuel from this process would cost $3 to $6 per gallon, including initial start-up costs. The report cited the Navy’s 2011 average cost for JP-5 at $3.51; media reports have put that number closer to $4. These prices don’t include shipping and storage costs, which would be cut drastically or eliminated by making JP-5 at sea.

“Historical data suggest that in nine years, the price of fuel for the Navy could be well over the price of producing a synthetic jet fuel at sea, which would not incur the costs associated with logistical storage and delivery,” the study says. “The analysis also serves to illustrate that the estimated initial capital costs associated with jet fuel production (reactor, electrolysis equipment, carbon capture) are far less than the capital costs of developing the [ocean thermal energy conversion method] or nuclear platforms at sea with which to produce the jet fuel.”

Navy Secretary Ray Mabus has set goals to cut the Navy and Marine Corps’ use of fossil fuels, calling for using alternative fuels for 50 percent of the Navy Department’s total energy usage by 2020.

His plan has come under attack, largely from Republicans, who say the Navy should not pursue alternative fuel programs until such fuels are more cost-effective. The Navy’s work in alternative liquid fuels has used a blend of traditional fuels mixed with an algae- or camelina-based fuel.